Boosters Carry Flawed History

Nearly Caused Disaster In `83

February 03, 1986|By Storer Rowley and James Coates. Also contributing to this article were Ronald Kotolak and Mark Eissman in Chicago, Ann Marie Lipinski at Cape Canaveral and Christopher Drew in New orleans.

Solid rocket boosters, like the one now emerging as a prime suspect in last week`s explosion of the space shuttle Challenger, showed serious flaws twice before last Tuesday`s launch and almost caused a catastrophe during the eighth shuttle flight in 1983.

Late last year, NASA sharply criticized the way the two boosters for the Challenger mission were being assembled at Cape Canaveral, citing faulty equipment, ill-trained workers and a failure to follow prescribed procedures. Film released by NASA on Saturday revealed an ``unusal plume`` of flame in the lower part of Challenger`s right booster. On Sunday, William Graham, NASA`s acting administrator, cautioned that the agency still had not determined what, if any, role the plume played in the Challenger disaster, but he described it as ``a situation which we have never seen on a launch of a shuttle before.``

The discovery of the plume lent added support to what has become the principal theory about the blast--that hot gasses leaking from the shuttle`s right booster somehow ignited liquid oxygen in the craft`s external fuel tank. On Nov. 8, workers using an overhead crane to assemble Challenger`s left booster cracked a section of the rocket, which had to be replaced, according to an internal NASA report on the incident.

The report cited no specific problems with the assembly of the right rocket booster, but it called for the use of more reliable equipment when putting the 149-foot rockets together from 11 individual weld-free segments of 1/2-inch steel. The report also called for training to make assembly workers more qualified and more responsible.

After being detached, the boosters parachute to the sea where they are recovered for reuse in future shuttlel missions. On the average, ninety-five percent of the hardware in the boosters on any shuttle mission have already been used at least once and often several times on earlier missions.

NASA has declined thus far to provide the past flight history of the parts used in the suspect right booster of the Challenger shuttle.

Although Graham said Sunday that NASA designers thought the rocket boosters were ``not susceptible to failure,`` there had been serious flaws found in other rockets employed before the Challenger mission.

During the eighth shuttle launch, flame from a booster came within seconds of burning through a critical heat shield protecting its nozzle near the bottom. The inside of the bell-shaped nozzle is covered with a 3-inch-thick layer of material that deflects the intense heat of thre intensely burning rocket.

Despite the fact that the shield is constructed to withstand the rocket`s 6,000 degree flame for 240 seconds--almost twice as long as the boosters remain attached to a shuttle during normal launch--is the shield was burning so rapidly that it was in danger of burning through entirely.

Astronaut Daniel Brandenstein, pilot for the eight mission, said afterwards that the nozzle would have burned through if the rocket had fired for another 2.7 seconds and that such a burn through would have destroyed the craft and killed the five astronauts aboard.

NASA officials put the time remaining before a burn through at 15 to 20 seconds.

``We did not have a burn through, but it came close,`` said former NASA engineer James Mizell on Sunday. ``If the solid rocket booster had run for another--I`ve forgotten, how many seconds or so--it may have burned through.`` NASA technicians have also sporadically found after missions traces of propellant soot that have gotten through the preliminary seal on booster joints. According to Mizell, the soot is a sign that exhaust gas is edging through the joints.

``These were the very first inklings that something like what happened on Tuesday`s flight was possible,`` NASA spokesman Charles Redmond said Sunday.

Despite the cran-related incident in November and the past history of problems with boosters, NASA officials seemed confident that the boosters were fully ready for the Challenger mission. During a high-level, teleconference hookup of officials from three space centers with agency directors in Washington only ``five or ten minutes`` out of a three hour meeting were devoted to discussing recent design changes in the boosters, Redmond said.

According to a copy of the readiness review report, the boosters had been changed to improve the parachutes which aid the decline of the reusable rockets into the ocean after they have been detached from the rest of the shuttle.

When asked if any concern had been voiced about the safety of the boosters, Redmond, said: ``I wouldn`t say no concern, but we felt as if we had licked a lot.``

The readiness report concluded that there were ``no major problems or issues`` with the boosters. It was signed by the chief engineer and the manager of the SRB Project; the vice president in charge of the Space Booster Program; and the executive vice president of United Space Boosters Inc.-Booster Production Co.